1. Field of the Invention
The invention relates to bar code readers having an extended range of working distances in which to read bar code symbols, as well as laser pointers and marking implements combined integrally with such readers.
2. Description of the Related Art
Various optical scanning systems and readers have been developed heretofore for reading indicia such as bar code symbols appearing on a label or on the surface of an article. The bar code symbol itself is a pattern of graphic indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers function by electro-optically transforming the spatial pattern represented by the graphic indicia into a time-varying electrical signal, which is in turn decoded into data which represent the information or characters encoded in the indicia that are intended to be descriptive of the article or some characteristic thereof. Such data is typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control, distribution, transportation and logistics, and the like.
A variety of scanning devices is known. The scanner could be a wand type reader, such as shown in U.S. Pat. No. 5,508,504, herein incorporated by reference, including a light emitter and a detector fixedly mounted in the wand, in which case the user manually moves the wand across the symbol. As the wand passes over the bar code, the emitter and associated optics produce a light spot on the symbol, and the detector senses the light reflected back from the light spot passing over each bar and space of the symbol. Alternatively, an optical moving spot scanner scans a light beam, such as a laser beam, across the symbol; and a detector senses reflected light from the beam spot scanned across the symbol. In each case, the detector produces the analog scan signal representing the encoded information.
Moving spot scanners of this general type have been disclosed for example, in U.S. Pat. Nos. 4,387,297; 4,409,470; 4,760,248; 4,896,026; 5,015,833; 5,262,627; 5,504,316; and 5,625,483, all of which have been assigned to the same assignee as the instant application and each of which is hereby incorporated by reference. As disclosed in some of the above patents, one embodiment of such a scanning system resides, inter alia, in a hand-held, portable laser scanning device supported by a user, which is configured to allow the user to aim the scanning head of the device, and more particularly, a light beam, at a targeted symbol to be read.
The light source in a laser scanner bar code reader is typically a semiconductor laser. The use of semiconductor devices as the light source is especially desirable because of their small size, low cost and low voltage requirements. The laser beam is optically modified, typically by an optical assembly, to form a beam spot of a certain size at the target distance. It is often preferred that the cross section of the beam spot measured in the scanning direction at the target distance be approximately the same as the minimum width in the scanning direction between regions of different light reflectivity, i.e., the bars and spaces of the symbol. Although typical readers utilize a single laser source, other bar code readers have been proposed with two or more light sources of different characteristics, e.g., different frequencies.
In the laser beam scanning systems known in the art, a single laser light beam is directed by a lens or other optical components along the light path toward a target that includes a bar code symbol on the surface. The moving-beam scanner operates by repetitively scanning the light beam in a line or series of lines across the symbol by means of motion of a scanning component, such as the light source itself or a mirror disposed in the path of the light beam. The scanning component may either sweep the beam spot across the symbol and trace a scan line across the pattern of the symbol, or scan the field of view of the scanner, or do both. The laser beam may be moved by optical or opto-mechanical means to produce a scanning light beam. Such action may be performed by either deflecting the beam (such as by a moving optical element, such as a mirror) or moving the light source itself. U.S. Pat. No. 5,486,944 describes a scanning module in which a mirror is mounted on a flex element for reciprocal oscillation by electromagnetic actuation. U.S. Pat. No. 5,144,120 to Krichever et al., describes laser, optical and sensor components mounted on a drive for repetitive reciprocating motion either about an axis or in a plane to effect scanning of the laser beam.
The light beam is focused to the beam spot at a focal point, and the symbol is located within a depth of field at either side of the focal point. This depth of field represents the working distance in which the symbol can be successfully read. A symbol outside this working distance is not readable.
Because of the size and optical and electronic complexity of scanning systems and bar code readers, they generally have heretofore not been combined with writing or marking instruments or laser pointers in the same housing.